Reaction turbine configuration

Abstract

The present disclosure provides a configuration of a system that includes a turbine with impeller section and a nozzle section peripheral and downstream the impeller section. The turbine is a two-phase reaction turbine that employs an isothermal expansion process within its nozzle section. Heat transfer liquid (HTL) and working fluid (WF) are mixed prior to entering the nozzle. The mixture of the HTL and the WF starts at a high pressure Pl at the inlet of the nozzle and ends at a low pressure PO at the outlet of the nozzle, therefore the WF expands within the nozzle and provides kinetic energy to the HTL and therefore to the mixture that causes the acceleration of the mixture towards the outlet of the nozzle. Since all the process is carried out on a rotating turbine, the mixture may tend to be pushed to the walls of the nozzle by the rotational forces as a result of non-symmetrical forces applied on the mixture, which can affect the efficiency of the energy production by the turbine. In order to eliminate such non-symmetrical forces, the nozzle is designed with a curved shape such that the center of mass of the mixture that flows in the nozzle flows at a straight line from a frame the perspective of the inertial system. Namely, the curvature profile of the nozzle is determined according to the intended RPM operation of the turbine. In other words, the nozzle is designed such that the forces acting on the mixture flow in the nozzle causing its center of mass to flow along a flow path that is in the center of the nozzle, at a given operational rotational velocity.

Description

[0001] REACTION TURBINE CONFIGURATION

[0002] TECHNOEOGICAE FIELD

[0003] The present disclosure is in the field of reaction turbines.

[0004] BACKGROUND ART

[0005] References considered to be relevant as background to the presently disclosed subject matter are listed below:

[0006] - WO 2022 / 049573

[0007] - WO 2024 / 062465

[0008] Acknowledgement of the above references herein is not to be inferred as meaning that these are in any way relevant to the patentability of the presently disclosed subject matter.

[0009] GENERAL DESCRIPTION

[0010] The present disclosure provides a unique configuration of a system that includes a turbine with impeller section and a nozzle section peripheral and downstream the impeller section. The turbine is a two-phase reaction turbine that employs an isothermal expansion process within its nozzle section. Heat transfer liquid (HTL) and working fluid (WF) are mixed prior to entering the nozzle. The WF is either a priori mixed in a vapor phase or evaporates after mixing with the HTL and being heated thereby. The mixture of the HTL and the WF starts at a high pressure Pl at the inlet of the nozzle and ends at a low pressure P0 at the outlet of the nozzle, therefore the WF expands within the nozzle and provides kinetic energy to the HTL and therefore the mixture that causes the acceleration of the mixture towards the outlet of the nozzle. The WF is constantly heated by the HTL during the expansion and therefore maintains at about the same temperature as the heat capacity of the HTL is greater than the heat capacity of the WF at about 3 orders of magnitude, resulting in a quasi-isothermal expansion. Since all the process is carried out on a rotating turbine, the mixture may tend to be pushed to the walls of the nozzle by the rotational forces as a result of non-symmetrical forces applied on the mixture. Such forces may result in a non-homogeneous mixture with the separation of the gaseous phase and the liquid phase in the mixture that can affect the efficiency of the energy production by the turbine. In order to eliminate such non-symmetrical forces, the nozzle is designed with a curved shape such that the center of mass of the mixture that flows in the nozzle flows at a straight line from a frame the perspective of the inertial system. The degree of the curvature of the nozzle at each of its parts that supports the straight line flow, which is not necessarily along the entire nozzle, is defined by one or both ofthe following parameters: (1) the operational rotational velocity ofthe turbine and (2) the radial injection location of the WF into the HTL with respect to the rotation axis of the turbine. The operational rotational velocity is defined by the typical revolutions per minute (RPM) that the turbine is designed to work in. Namely, the curvature profile of the nozzle is determined according to the intended RPM operation of the turbine. In other words, the nozzle is designed such that the forces acting on the mixture flow in the nozzle causing its center of mass to flow along a flow path that is in the center of the nozzle. From the perspective of the inertial system, which is the inertial frame of reference and is with stationary coordinates, the flow path of the center of mass of the flow of the mixture is a straight line and the nozzle is designed to support this straight-line flow. Optionally, part of the nozzle supports a flow in a straight line in the inertial system. Optionally only the last 10%, 20%, or 50% of the nozzle supports flow in a straight line in the inertial system.

[0011] Therefore, an aspect of the present disclosure provides a turbine system. The turbine system comprises a rotatable turbine rotating about a rotation axis of rotation within an inertial frame of reference, The turbine comprises a heat transfer liquid (HTL) inlet for allowing receiving a stream of HTL. The turbine further comprises an impeller section in fluid communication with and radially peripheral to the HTL inlet to receive said stream of HTL, the impeller section is configured to elevate the pressure of HTL received thereinto to PL The turbine further comprises a nozzle section radially peripheral to the impeller section and defining one or more nozzles; a working fluid (WF) injector for injection of pressurized WF into a mixing section, typically at about the pressure of the HTL in that section, for mixing a working fluid (WF) and the HTL to form a WF / HTL mixture, the mixing section is either defined in the impeller section, the nozzle section or in a section linking the impeller section and the nozzle section. The impeller section, the mixing section and the nozzle section define a center of mass flow path of the HTL and the WF / HTL mixture. The center of mass flow path defines the flow path of the center of the flow of the HTL or the WF / HTL mixture in a cross section portion at any one of the sections of the turbine . The center of mass flow path is affected by the geometry of the blades of the impeller and the geometry of the walls of the nozzle. The nozzle is designed for (i) receiving the WF / HTL mixture from the mixing section, (ii) allowing isothermal or quasi-isothermal expansion of the WF to thereby accelerating the WF / HTL mixture and (iii) ejection of the accelerated WF / HTL mixture from an outlet of the nozzle to induce rotation of the turbine, namely the turbine is a reaction turbine. For a given operational rotational velocity of the turbine and an injection of WF at a specific radial distance from the axis of rotation, at least a part of the nozzle is designed for supporting that the center of mass flow path of the nozzle section is a straight streamlined flow of a controlled volume of the WF / HTL mixture in the inertial system / inertial frame of reference, namely the system / frame of reference with the stationary coordinates. In other words, at a given operational rotational velocity of the turbine, at least a part of the center of mass flow path of a streamlined flow of a controlled volume of the WF / HTL mixture is a straight line in the inertial frame of reference. The term “controlled volume” should be understood as a portion of WF / HTL mixture that its dynamic behavior is examined overtime.

[0012] Practically, different physical properties, such as friction at the flow boundaries, change the flow compared to the ideal flow. For example, different boundaries have different relative velocities to the flow, leading to non-symmetrical friction forces on the flow. Computational Fluid Dynamic (CFD) simulation, takes into account friction and other factors, such as gradients in pressure along the nozzle cross-section. Optionally the flow is a straight line at the inertial system of reference according to these effects. Optionally the flow is a straight line at the inertial system of reference according to CFD. Also, the desired flow path can be observed experimentally. For example, a transparent nozzle is monitored by a fixed camera (viewing from the inertial system of reference). The camera captures the straight-line flow of the bubbly media accelerating in the nozzle. Optionally the flow is a straight line at the inertial system of reference according to real experiments. It is to be noted that any combination of the described embodiments with respect to any aspect of this present disclosure is applicable. In other words, any aspect of the present disclosure can be defined by any combination of the described embodiments.

[0013] In some embodiments of the system, the nozzle section is characterized by: (1) in a first part or at least a first part of the center of mass flow path, in which a tangential velocity of flow along the center of mass flow path is lower than a tangential velocity of the turbine at the location of the flow path in the first part, a radial distance of the center of mass flow path from the rotation axis increases along a downstream direction of the flow path, (2) in a second part of the center of mass flow path, in which the tangential velocity of the flow along the center of mass flow path is higher than the tangential velocity of the turbine at the location of the flow path in the second part, a radial distance of the center of mass flow path from the rotation axis decreases along a downstream direction of the flowpath; wherein the first part and the second part are designed to create a straight line flow in an inertial system defined by the turbine. Namely, from the point of view of the inertial system, the flow of the HTL / WF mixture in the nozzle section is generally a straight line. This is important in order to eliminate non-symmetrical forces on the bubbly flow of the mixture, which may separate the flow or cause a non-uniform pressure. The operation rotational velocity of the turbine is the characteristic rotational velocity in the desired and characteristic mode of operation. Typically, the turbine is designed to operate optimally in this characteristic rotational velocity. It is to be noted that when referring to a comparison between tangential velocities throughout the application, the comparison is performed between the absolute values of the velocities as the tangential velocity of the turbine and the tangential velocity of the flow along the flow path are in opposite directions. It is noted that the tangential velocity of the turbine is the rotation velocity (omega) times the distance from the axis of rotation and that the flow tangential velocity starts at similar values to the turbine tangential velocity and accelerates at the opposite direction, in particular in the nozzle.

[0014] In some embodiments of the system, the nozzle section is characterized by a radial distance increasing part being the at least one first part of the center of mass flow path, in which the center of mass flow path radial distance from the rotation axis increases, and a radial distance decreasing part downstream the radial distance increasing part and being the at least one second part of the center of mass flow path, in which the center of mass flow path radial distance from the rotation axis decreases. In some embodiments of the system, said first part of the center of mass flow path is upstream said at least one second part of the center of mass flow path.

[0015] In some embodiments of the system, center of mass flow path of the nozzle section is characterized by: at least one third part of the center of mass flow path within the nozzle section, in which a tangential velocity of the flow along the center of mass flow path is higher than the tangential velocity of the turbine at the location of the flow path in the third part, a radial distance of the center of mass flow path from the rotation axis increases along a downstream direction of the flow path; wherein said at least one third part of the center of mass flow path is downstream said at least one second part of the center of mass flow path. Namely, the nozzle is designed along the downstream direction with a first part, a second part and then a third part of the center of mass flow path.

[0016] Optionally, only a section of the three parts is realized, and only part of the flow is in a straight line. Optionally, only after the center mass flow line returns to the injection location, the third part is realized, and the streamline becomes a straight line in the inertial system.

[0017] In some embodiments of the system, the radial distance increasing part defines a first nozzle part, the first nozzle part is characterized by that a distance of its center of mass from the rotation axis increases, the center of mass is defining the central portion of a flow of fluid within the nozzle. The radial distance decreasing part defines a second nozzle part, the second nozzle part is characterized by that a distance of its center of mass from the rotation axis decreases.

[0018] In some embodiments of the system, the nozzle section is characterized by an additional radial distance increasing part, in which the center of mass flow path radial distance from the rotation axis increases. The additional radial distance increasing part is located downstream the radial distance decreasing part. Therefore, the order of the parts of the nozzle section along the flow direction is: (1) radial distance increasing part, (2) radial distance decreasing part and (3) additional radial distance increasing part.

[0019] In some embodiments of the system, the HTL inlet is at or defines the rotation axis.

[0020] In some embodiments of the system, the nozzle is a de Laval nozzle having a converging diverging geometry, where the neck of the nozzle is located between the converging and the diverging sections. In some embodiments of the system, the first part of the center of mass flow path or the radial distance increasing part is defined between the mixing section and a neck of the nozzle, and the second part of the center of mass flow path or the radial distance decreasing part is defined between the neck of the nozzle and the outlet of the nozzle. The neck of the nozzle defines the part of the nozzle in which its cross section is the minimal.

[0021] In some embodiments of the system, the third part of the center of mass flow path is defined between the neck and the exit of the nozzle.

[0022] In some embodiments of the system, center of mass flow path of the nozzle section is characterized by: a tangential part in which the center of mass flow path radial distance from the rotation axis is constant and a radial distance increasing part, in which a tangential velocity of a flow along the center of mass flow path is higher than the tangential velocity of the turbine and a radial distance of the center of mass flow path from the rotation axis increases; wherein said radial distance increasing part of the center of mass flow path is downstream said tangential part. Namely, the nozzle section is formed by a tangential part in which the center of mass flow path in the inertial system is not a straight line. In this part, the tangential velocity of a flow along the center of mass flow path increases with respect to the tangential velocity of the turbine until reaching about the tangential velocity of the turbine (the term about should be understood as ±20% of the nominal value). The radial distance increasing part starts when the tangential velocity of the flow reaches about the tangential velocity of the turbine in the opposite direction, leading to a zero velocity at the inertial system of reference.

[0023] In some embodiments of the system, the increase or decrease profile of the radial distance of the center of mass flow path from the rotation axis, namely the extent or the gradient of the increase or the decrease, in each selected location is defined based on the difference between the absolute tangential velocity of the flow along the flow path and the absolute turbine tangential velocity. This can be affected, among others, by the radial distance of the injection of the working fluid.

[0024] In some embodiments of the system, the increase or decrease profile of the radial distance of the center of mass flow path from the rotation axis, namely the extent or the gradient of the increase or the decrease, in each selected location is dependent on the relation between tangential velocity profile of the flow along the flow path and the turbine tangential velocity. In other words, the increase or decrease profile of the radial distance of the center of mass flow path from the rotation axis is defined based on the relation between the velocity and the acceleration of the flow in the specific location and the tangential velocity of the turbine in the specific location.

[0025] Therefore, the curvature profile of the nozzle that defines the center of mass flow path, and therefore the distance of the center of mass flow path from the rotation axis, changes along the nozzle. Namely, at each section of the nozzle that changes its distance from rotation axis, the degree of the change may vary according to the expected relation between the tangential velocity profile of the flow along the flow path and the tangential velocity of the turbine at the same location. The tangential velocity profile of the flow should be understood as the combination of the tangential velocity and the tangential acceleration of the flow at the specific location.

[0026] In some embodiments of the system, the straight streamline defining a flow of the controlled volume along a straight flow axis in the inertial system. It is to be noted that the center of mass flow path can be defined substantially along the straight flow axis with insignificant deviations from the straight flow axis and still be regarded as a straight streamline flow. Deviations from the straight flow axis of up to 10% or 5% of the effective length of the nozzle are regarded as a straight streamline flow.

[0027] In some embodiments of the system, the outlet of the nozzle is tilted with respect to an impeller plane defined by the impeller section so as to eject the WF / HTL mixture below or above the impeller to avoid impingement of the jet of the WF / HTL on the impeller or other turbine portions since the end of the nozzle is turning inwardly towards the impeller direction.

[0028] In some embodiments of the system, the impeller defines an impeller plane and outlet of the nozzle is located on an outlet plane parallel to and different from the impeller plane.

[0029] In some embodiments of the system, the outlet plane is lower than the impeller plane with respect to the ground.

[0030] In some embodiments of the system, the nozzle has a tilt profile with respect to the impeller plane such that it gradually decreases its height until reaching the outlet plane, forming a spiral flow along the flow path in the nozzle.

[0031] In some embodiments, the system further comprises a WF flow line fluidically coupled upstream to the WF injector for allowing a flow of WF to the WF injector, from a source of pressurized WF, such as a compressor, wherein the WF flow line is in thermal contact with portions of the impeller section for allowing heat exchange between the HTL flowing in the impeller section and WF flowing in the WF flow line.

[0032] In some embodiments, the system further comprises a WF heater fluidically coupled upstream to the WF injector for controllably heating the WF.

[0033] In some embodiments, the system further comprises a siphon section that comprises a siphon arrangement, the siphon section is located between the impeller section and the mixing section. Namely, the siphon section is located before the section in which the WF is injected and mixed with the HTL.

[0034] In some embodiments of the system, the mixing section is downstream of a highest static -pressure location defining the location in which the static pressure is the highest. This design ensures that no or limited backflow of WF will occur during ramp- up procedure of the turbine.

[0035] In some embodiments, the system further comprises a pre-impeller inducer upstream the HTL inlet for inducing positive pressure in a HTL flow line, i.e. a flow line that is the rotating turbine’s leg connecting the HTL inlet and a source of HTL, that is fluidically coupled to the HTL inlet. By inducing positive pressure in the HTL flow line, gas is prevented from entering into the HTL flow line. The pre-impeller inducer is optionally an additional pump. Optionally, the pre-impeller inducer is a shaft connected to the turbine.

[0036] In some embodiments, the system further comprises a HTL flow line fluidically coupled upstream to the HTL inlet at a first end thereof and is coupled to a fixed base at a second end thereof with sealed bearings to prevent gas from entering the impeller through the HTL flow line. The HTL flow line is rotatable with the turbine rotation.

[0037] Another aspect of the present disclosure provides a turbine system.

[0038] The turbine system comprises a heat transfer liquid (HTL) inlet for allowing receiving a stream of HTL; an impeller section in fluid communication with the HTL inlet to receive said stream of HTL, wherein the impeller section is configured to elevate the pressure of HTL received thereinto to P 1 ; a working fluid (WF) as vapor or liquid phase injection section peripheral to the impeller section, namely at outer diameter to the impeller section, for injection of pressurized WF at about a pressure of Pl, namely ±20% from P 1 , into the HTL that flows from the impeller; a mixing section to form a vapor / HTL mixture at about similar temperature; and a nozzle section peripheral to the mixing section that comprises a converging-diverging, De Laval, nozzle geometry portion, the nozzle section being peripheral to the mixing section and is configured for (i) receiving the WF / HTL mixture from the mixing section, wherein the WF in the De Laval nozzle geometry section is in gaseous phase, (ii) accelerating the WF / HTL mixture and (iii) reducing the pressure of the mixture to PO, thereby resulting in an isothermal expansion or quasi-isothermal expansion of the mixture; an outlet formed at the end of the nozzle section or downstream thereof for ejecting the accelerated WF / HTL to thereby generate thrust.

[0039] In some embodiments of the system, the WF is injected into the WF injection section in a liquid phase and the HTL heats it following the injection to cause the evaporation of the WF.

[0040] In some embodiments of the system, the WF is injected into the WF injection section in a gaseous phase.

[0041] In some embodiments of the system, said outlet is configured to result in a tangential ejection of the mixture. The tangential ejection defines that the mixture is ejected in a tangential angle with respect to the turbine outer diameter.

[0042] In some embodiments of the system, the De Laval nozzle geometry portion has a circular symmetry.

[0043] In some embodiments of the system, the De Laval nozzle geometry portion is formed by shape variation of a bottom wall and a top wall.

[0044] In some embodiments, the system further comprises first vanes formed at the impeller section, the WF injection section and the mixing section, and second vanes formed at the nozzle section, wherein the first vanes and the second vanes are continuous, namely they form a continuous vanes structure together.

[0045] In some embodiments of the system, the angle of first and second vanes with respect to the radius of the turbine is dependent on the radial position, namely the angle is changing for any vane as its distance from the turbine’s center changes.

[0046] In some embodiments of the system, the nozzle section is defined by the De Laval nozzle geometry portion and a change of the angle of the second vanes and the width of the opening formed by the two adjacent vanes that define the nozzle section. This configuration results in the drop of the pressure and the supersonic velocity of the mixture .

[0047] In some embodiments of the system, the WF / HTL mixture is supersonic in the De Laval nozzle geometry section. In some embodiments of the system, the mixture is ejected at an ejection angle that is about 90° with respect to the radius. The term “about” means that ejection angle can be between 70°-l 10° with respect to the radius.

[0048] In some embodiments of the system, the flow of the WF / HTL mixture has an average flow propagation direction along the flow path in the turbine, wherein the average flow direction propagation downstream the De Laval nozzle geometry portion is larger than 30° with respect to the average flow direction propagation upstream the De Laval nozzle geometry portion.

[0049] In some embodiments of the system, the HTL inlet is formed at a rotation axis of the system and the impeller.

[0050] In some embodiments of the system, the WF is injected as a liquid into the HTL wherein the liquid WF enters the turbine system from the axis of rotation of the system.

[0051] In some embodiments, the system further comprises a WF pump configured to maintain the WF in a liquid phase according to its temperature.

[0052] In some embodiments, the system further comprises WF vanes directing the WF towards the WF injection section, wherein the WF vanes are designed to bring the WF into the injection at about the same or slightly above pressure of the HTL, namely PL

[0053] In some embodiments of the system, the length of De Laval nozzle geometry portion is at least 2 times shorter than the length of the flow path in the nozzle section.

[0054] In some embodiments of the system, the mixing section is designed to maintain a fixed static pressure.

[0055] In some embodiments, the system further comprises vanes defining the impeller section, the mixing section and the nozzle section, wherein the vanes defining the nozzle section are continuous to the vanes defining the mixing section and the impeller section.

[0056] EMBODIMENTS

[0057] The following are optional embodiments and combinations thereof in accordance with aspects of the present disclosure:

[0058] 1. A method for a two-phase vapor / liquid or gas / liquid reaction turbine omnidirectional De Laval supersonic nozzle, having an impeller section in an inner diameter of the reaction turbine, an injection of the working fluid at an outer diameter of the impeller, a mixing section at an outer diameter of the injection section, and a De Laval nozzle geometry at the outer diameter to the mixing section.

[0059] 2. The method of embodiment 1, wherein the De Laval section is a cylindrical symmetry modulation, and its vanes continuing said impeller vanes.

[0060] 3. The method of embodiments 1 and 2, wherein the converging -diverging modulation in the radial direction is at least 2 times shorter than the distance of the flow in the nozzle.

[0061] 4. The method according to embodiments 1 -3 , wherein the supersonic j et emerges at above 90% of all angles.

[0062] 5. The method according to any of the above embodiments wherein in the nozzle section after the injection, the flow propagation direction is at an angle with respect to the converging-diverging radial modulation that is larger than 30 deg.

[0063] 6. The method according to any of the above embodiments wherein the drop in the pressure and acceleration of the mixture to supersonic conditions is by using a combination of two geometry properties, one is convergence- divergence of the rotor height and the other is by changing the vane angle.

[0064] 7. The method according to any of the preceding embodiments, wherein the WF is injected as a liquid into the HTL wherein the liquid WF enters the turbine from the axis of rotation.

[0065] 8. The method according to embodiment 7, wherein the WF pump maintains the WF as a liquid according to its temperature.

[0066] 9. The method according to embodiment 7, wherein vanes at the WF flow control the pressure of the WF to pass the injection and reach the HTL at the same or slightly above pressure as the HTL.

[0067] 10. A turbine system, comprising: a heat transfer liquid (HTL) inlet for allowing receiving a stream of HTL; an impeller section in fluid communication with the HTL inlet to receive said stream of HTL, wherein the impeller section is configured to elevate the pressure of HTL received thereinto to Pl; a working fluid (WF) injection section peripheral to the impeller section for injection of pressurized WF at about a pressure of Pl into the HTL that flows from the impeller; a mixing section to form a vapor / HTL mixture at about similar temperature; and a nozzle section peripheral to the mixing section that comprises a convergingdiverging, De Laval, nozzle geometry portion, the nozzle section being peripheral to the mixing section and is configured for (i) receiving the WF / HTL mixture from the mixing section, wherein the WF in the De Laval nozzle geometry section is in gaseous phase, (ii) accelerating the WF / HTL mixture and (iii) reducing the pressure of the mixture to PO, thereby resulting in an isothermal expansion or quasi-isothermal expansion of the mixture; an outlet formed at the end of the nozzle section or downstream thereof for ejecting the accelerated WF / HTL to thereby generate thrust.

[0068] 11. The system of embodiment 10, wherein the WF is injected into to the WF injection section in a liquid phase and the HTL heats it following the injection to cause in the evaporation of the WF.

[0069] 12. The system of embodiment 10, wherein the WF is injected into the WF injection section in a gaseous phase.

[0070] 13. The system of any one of embodiments 10-12, wherein said outlet is configured to result in a tangential ejection of the mixture.

[0071] 14. The system of any one of embodiments 10-13, wherein the De Laval nozzle geometry portion has a circular symmetry.

[0072] 15. The system of any one of embodiments 10-14, wherein the De Laval nozzle geometry portion is formed by shape variation of a bottom wall and a top wall.

[0073] 16. The system of any one of embodiments 10-15, comprising first vanes formed at the impeller section, the WF injection section and the mixing section, and second vanes formed at the nozzle section, wherein the first vanes and the second vanes are continuous.

[0074] 17. The system of embodiment 16, wherein the angle of first and second vanes with respect to the radius of the turbine is dependent on the radial position.

[0075] 18. The system of embodiment 17, wherein the nozzle section is defined by the De Laval nozzle geometry portion and a change of the angle of the second vanes.

[0076] 19. The system of any one of embodiments 10-18, wherein the WF / HTL mixture is supersonic in the De Laval nozzle geometry section.

[0077] 20. The system of any one of embodiments 10-19, wherein the mixture is ejected at an ejection angle that is about 90° with respect to the radius.

[0078] 21. The system of any one of embodiments 10-20, wherein the flow of the WF / HTL mixture has an average flow propagation direction along the flow path in the turbine, wherein the average flow direction propagation downstream the De Laval nozzle geometry portion is larger than 30° with respect to the average flow direction propagation upstream the De Laval nozzle geometry portion.

[0079] 22. The system of any one of embodiments 10-21, wherein the HTL inlet is formed at a rotation axis of the system.

[0080] 23. The system of any one of embodiments 10-22, wherein the WF is injected as a liquid into the HTL wherein the liquid WF enters the turbine system from the axis of rotation of the system.

[0081] 24. The system of embodiment 23, comprising a WF pump configured to maintain the WF in a liquid phase according to its temperature.

[0082] 25. The system of embodiment 23 or 24, comprising WF vanes directing the WF towards the WF injection section, wherein the WF vanes are designed to bring the WF into the injection at about the same or slightly above pressure of the HTL.

[0083] 26. The system of any one of embodiments 10-25, wherein the length of De Laval nozzle geometry portion is at least 2 times shorter than the length of the flow path in the nozzle section.

[0084] 27. The system of any one of embodiments 10-26, wherein the mixing section is designed to maintain a fixed static pressure.

[0085] 28. The system of any one of embodiments 10-27, comprising vanes defining the impeller section, the mixing section and the nozzle section, wherein the vanes defining the nozzle section are continuous to the vanes defining the mixing section and the impeller section.

[0086] 29. A turbine system, comprising: a rotatable turbine rotating about a rotation axis of rotation within an inertial frame of reference, and having a heat transfer liquid (HTL) inlet for introducing a stream of HTL, an impeller section in fluid communication with and radially peripheral to the HTL inlet to receive said stream of HTL, a nozzle section radially peripheral to the impeller section and defining one or more nozzles, and a working fluid (WF) injector for injection of pressurized WF into a mixing section for mixing a working fluid (WF) and the HTL to form a WF / HTL mixture, the mixing section is either defined in (i) the impeller section, (ii) the nozzle section or (iii) in a section linking the impeller section and the nozzle section; wherein the impeller section, the mixing section and the nozzle section define a center of mass flow path of the HTL and of the WF / HTL mixture, the nozzle is designed for (i) receiving the WF / HTL mixture from the mixing section, (ii) allowing isothermal or quasi-isothermal expansion of the WF thereby accelerating the WF / HTL mixture and (iii) ejection of the accelerated WF / HTL mixture from an outlet of the nozzle to induce rotation of the turbine, and wherein at a given operational rotational velocity of the turbine, at least a part of the center of mass flow path of a streamlined flow of a controlled volume of the WF / HTL mixture is a straight line in the inertial frame of reference.

[0087] 30. The turbine system of embodiments 29 , wherein for at least one first part of the center of mass flow path, in which a tangential velocity of flow along the center of mass flow path is lower than a tangential velocity of the turbine, a radial distance of the center of mass flow path from the rotation axis increases along a downstream direction of the flow path, for at least one second part of the center of mass flow path, in which the tangential velocity of the flow along the center of mass flow path is higher than the tangential velocity of the turbine, a radial distance of the center of mass flow path from the rotation axis decreases along a downstream direction of the flow path, and wherein the first part and the second part are designed to create a straight line flow in the inertial frame of reference.

[0088] 31. The turbine system of embodiment 30, wherein said first part of the center of mass flow path is upstream said second part of the center of mass flow path.

[0089] 32. The turbine system of embodiment 30 or 31, wherein for at least one third part of the center of mass flow path within the nozzle section, in which a tangential velocity of the flow along the center of mass flow path is higher than the tangential velocity of the turbine, a radial distance of the center of mass flow path from the rotation axis increases along a downstream direction of the flow path, and wherein said at least one third part of the center of mass flow path is downstream said at least one second part of the center of mass flow path. 33. The turbine system of any one of embodiments 29-32, wherein the nozzle section comprises a radial distance increasing part, in which the center of mass flow path radial distance from the rotation axis increases, and a radial distance decreasing part downstream the radial distance increasing part and, in which the center of mass flow path radial distance from the rotation axis decreases.

[0090] 34. The turbine system of embodiment 33, wherein the radial distance increasing part defines a first nozzle part in which distance of its center of mass from the rotation axis increases, and the radial distance decreasing part defines a second nozzle part, the second nozzle part in which distance of its center of mass from the rotation axis decreases.

[0091] 35. The turbine system of any one of embodiments 29-34, wherein the HTL inlet is at the rotation axis.

[0092] 36. The turbine system of any one of embodiments 29-35, wherein the nozzle is a de Laval nozzle having a de Laval nozzle geometry.

[0093] 37. The turbine system of any one of embodiments 30-36, wherein the at least one first part of the center of mass flow path or the radial distance increasing part is defined between the mixing section and a neck of the nozzle, and the at least one second part of the center of mass flow path or the radial distance decreasing part is defined between the neck of the nozzle and the outlet of the nozzle.

[0094] 38. The turbine system of any one of embodiments 29-37, wherein the increase or decrease profile of the radial distance of the center of mass flow path from the rotation axis in each selected location is dependent on the difference between the tangential velocity of the flow along the flow path and the turbine tangential velocity.

[0095] 39. The turbine system of any one of embodiments 29-38, wherein the outlet of the nozzle is tilted with respect to an impeller plane defined by the impeller section so as to eject the WF / HTL mixture below or above the impeller.

[0096] 40. The turbine system of any one of embodiments 29-39, wherein the impeller defines an impeller plane and outlet of the nozzle is located on an outlet plane parallel to and different from the impeller plane.

[0097] 41. The turbine system of embodiment 40, wherein the outlet plane is lower than the impeller plane. 42. The turbine system of embodiment 40 or 41, wherein the nozzle has a tilt profile with respect to the impeller plane such that it gradually decreases its height until reaching the outlet plane.

[0098] 43. The turbine system of any one of embodiments 29-42, comprising a WF flow line fluidically coupled upstream to the WF injector for allowing a flow of WF to the WF injector, wherein the WF flow line is in thermal contact with portions of the impeller section for allowing heat exchange between the HTL flowing in the impeller section and WF flowing in the WF flow line.

[0099] 44. The turbine of any one of embodiments 29-43, comprising a WF heater fluidically coupled upstream to the WF injector for controllably heating the WF.

[0100] 45. The turbine of any one of embodiments 29-44, comprising a siphon section that comprises a siphon arrangement, the siphon section is located between the impeller section and the mixing section.

[0101] 46. The turbine of any one of embodiments 29-45, wherein the mixing section is downstream of a highest static -pressure location defining the location in which the static pressure is the highest.

[0102] 47. The turbine system of any one of embodiments 29-46, comprising a pre-impeller inducer upstream the HTL inlet for inducing positive pressure in a HTL flow line that is fluidically coupled to the HTL inlet.

[0103] 48. The turbine system of any one of embodiments 29-47, comprising a HTL flow line fluidically coupled upstream to the HTL inlet at a first end thereof and is coupled to a fixed base at a second end thereof with sealed bearings, wherein the HTL flow line is rotatable with the turbine rotation.

[0104] BRIEF DESCRIPTION OF THE DRAWINGS

[0105] In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

[0106] Fig 1 is a schematic illustration of a conventional De-Laval two-phase nozzle having a converging diverging shape. Fig. 2 is a schematic illustration of a two-phase reaction turbine using conventional nozzles.

[0107] Fig. 3 is a schematic illustration of omnidirectional De-Laval nozzle for two- phase flow.

[0108] Fig. 4 is a schematic illustration of an inner section of a reaction turbine that acts as an impeller.

[0109] Fig. 5 is a schematic illustration showing injection of the liquid working fluid through pipes.

[0110] Fig. 6 is a schematic illustration of a curved nozzle that induces a straight streamline in the inertial system.

[0111] Fig. 7 is a schematic illustration showing an impeller with a siphon section.

[0112] Fig. 8 is a schematic illustration of a curved line path that induces a straight streamline in the inertial system.

[0113] DETAILED DESCRIPTION

[0114] The following figures are provided to exemplify embodiments and realization of the invention of the present disclosure.

[0115] The present disclosure provides a new type of reaction turbine that enables a near isothermal expansion of the working fluid (WF) for gaining the maximal work possible at a given operational temperature. Isothermal expansion is obtained by a flow of pressurized WF bubbles in a heat transfer liquid (HTL) media while pressure is dropped. The high contact area between the phases and the difference in the phases’ heat capacities allow the WF bubbles to expand while absorbing heat from the HTL and maintaining a near-constant temperature we name quasi-isothermal. The expanding bubbles perform work on the HTL that gains kinetic energy that is converted to shaft work. The WF operating the turbine can be either compressed gas or liquid that goes through a phase change to gas when mixed with the HTL.

[0116] The conventional method is connecting an HTL pump to a two-phase nozzle, where the WF is injected, and the isothermal expansion generates thrust that drives a Pelton turbine, for generating electricity. However, this method is lossy. Centrifugal pump has 80% efficiency mainly due to the stator. In the nozzle, the pressure should reach a maximal value, which requires converting the incoming velocity to pressure, a process that has significant head losses. Next, the Pelton turbine efficiency is about 90% efficiency. Together 60%-70% is the maximal expected turbine efficiency. In addition, at the exit of the Pelton, the two-phase mixture is at zero velocity and must be separated for recycling in the turbine, which requires additional energy loss.

[0117] A reaction turbine is an ideal solution for replacing the pump, nozzle, and Pelton at higher efficiency. The inner diameter section is optionally operated as a pump impeller, without a stator. At the radial edge of the impeller pump section, the HTL velocity is nearly the same as the impeller velocity resulting in a maximal static (nearly the stagnation) pressure. At this diameter, the bubbles should be injected or formed. A mixing section optionally follows the injection section and allows reaching the same temperature mixture. Optionally the mixing chamber is designed to maintain fixed pressure. At the outer diameter of the mixing chamber, the pressure is reduced by a two-phase nozzle, converting the pressure to kinetic energy, generating thrust that is converted to electricity. The non-zero end-velocity of the mixture exiting the nozzle, which is associated with a reaction turbine, is used to separate the mixture by generating a film flow on a curved, optional circular, surface.

[0118] Optionally, the flow in the nozzle is supersonic, this is because the speed of sound in a two-phase mixture is in the order of 20 meters per second, which can easily be reached at a pressure difference reduction level above 5 Bar. This requires a De-Laval supersonic nozzle that was previously modified to a two-phase flow. Such De Laval nozzle has a cylindrical symmetry a converging diverging shape and the flow average direction is the axis of symmetry. In other words, the average flow is of De-Laval nozzle, namely it is at a straight line at the nozzle’s coordination system. Fig. 1 depicts an example of a cylindrical symmetry De Laval nozzle (DLN), where the flow is at the symmetry axis direction. The problem is that the ideal exit flow in the reaction turbine is tangential while the conventional straight nozzle’s jet must have a non-tangential exit angle. This angle is a source of loss and should be avoided. Fig. 2 depicts these conditions. The WF injection is at the inlet of the nozzle where the static pressure is set to be the highest.

[0119] The present disclosure provides several solutions for dealing with these head losses. One solution is to curve the nozzle, to form a straight-line flow in the inertial system, which is detailed below. Another solution is to avoid such losses by an omnidirectional supersonic nozzle. It is noted that for the same size (diameter and height) limit on the turbine size, an omnidirectional nozzle can generate the maximal thrust compared to any other geometry, by allowing maximal outlet cross-section and maximal outlet area which allows a mass flow.

[0120] In general, an ideal omnidirectional DLN has unique features from any other nozzle, specifically:

[0121] • In an omnidirectional DLN, the outer flow is quasi-uniform, nearly tangential, in all directions, while in conventional DLN the outlet flow is at a small portion from the entire 360-degree directions.

[0122] • In an omnidirectional DLN, equal pressure lines are Quasi-radial, while in conventional DLN the equal pressure lines are perpendicular to the flow.

[0123] • In an omnidirectional DLN, the flow in the nozzle section is nearly tangential, that is nearly parallel to the equal pressure lines, while in conventional DLN the flow is perpendicular to the equal pressure lines.

[0124] • In an omnidirectional DLN the converging expanding geometry is quasi radial according to the pressure lines.

[0125] • In conventional DLN the converging section aims to accelerate the velocity to reach Mach-1 at the narrow section (see Fig. 1). In omnidirectional DLN the acceleration of the flow with respect to the turbine is achieved partially by reaching longer radial distances where the tangential velocity is higher. Therefore, reaching Mach-1 may not require a converging section as narrow as in conventional DLN, which reduces head losses. Figure 3 depicts an omnidirectional DLN horizontal cross-section (left) and vertical cross-section (right).

[0126] The turbine has an impeller section in the inner diameter of the reaction turbine, an injection of the working fluid at the outer diameter of the impeller, and a De Laval nozzle geometry at the outer diameter of the injection. The HTL flows from the bottom and is sucked by the impeller, reaching the impeller and building the pressure as in a centrifugal pump. The dashed diameter defines the edges of the impeller where the stagnation pressure is the highest. At the impeller, the radial velocity is defined by the flow rate and is very slow. The HTL rotates in the impeller, and its tangential velocity is near the impeller’s rotation velocity in each different diameter. Due to the low velocity of the HTL with respect to the impeller at the dashed line, the static pressure is close to the stagnation pressure, allowing to inject the gas or vapor at the highest pressure, generating maximal power of expansion. Optionally, liquid / vapor phase changing (LVPC) material is injected to be vaporized near or at the maximal static pressure diameter. The working fluid (WF) is the LVPC after evaporation, namely the WF is injected in vapor phase. In another embodiment, the injection of the LVPC is at a shorter diameter to allow evaporation, by being heated by the HTL, while reaching the dashed line diameter. Optionally, evaporation occurs in the mixing chamber or in the nozzle at a diameter equal to or longer than the dashed line. Optionally, at longer diameters than the injection, the geometry is constructed of a cylindrically symmetric converging -diverging modulation is at the radial direction and vanes that continue the impeller vanes having different angles. We note that the converging-diverging modulation in the radial direction is at least 2 times shorter than the distance of the flow in the nozzle. Optionally, the converging -diverging modulation in the radial direction is at least 3, 5 10, or 20 times shorter than the distance of the flow in the nozzle. Optionally, the radial modulation has a length between 5mm to 300mm (converging-diverging gray section after the dashed line diameter in Figure 3), which is much shorter than the flow propagation length in this section having an order of magnitude longer distance. This is very different than in conventional DLN (Fig. 1) where the converging-diverging length is the same as the flow propagation length in the nozzle. This is because of the near-tangential flow direction in the omnidirectional DLN that is nearly perpendicular to the radial direction and therefore requires a long flow propagation to reach a small radial distance. That is, in the nozzle section after the injection, the flow propagation direction is at an angle with respect to the converging-diverging radial modulation that is larger than 30 deg. Optionally, this angle is larger than 60 deg, 80 deg, or near tangential, which is approximately 90 deg.

[0127] The impeller vanes allow the entire impeller to work on the liquid in an omnidirectional way. That is, the liquid is pushed in the radial direction at all angles, and without the stator would exhibit omnidirectional radial flow except where the vanes are located where there is no flow. The vanes at the nozzle have the same advantage, as they operate on the entire turbine forming a supersonic jet that is quasi -uniform in all directions except where the vanes are. This is referred to as the omnidirectional De Laval nozzle. Optionally, the supersonic jet emerges at above 90% of all angles. Optionally, the supersonic jet emerges at above 80%, 70%, or 50% of all angles. It is noted that when changing the flow parameters, for example, HTL flow rate, gas or vapor mass flow rate, HTL inlet pressure, gas or vapor inlet pressure, HTL temperature, or any other physical parameter, then the DLN design is not optimal, and its operation is “off-design”. Optionally, at off-design, a change in the DLN geometry improves its operation. Optionally, the nozzle vanes rotate a few degrees around their contact point with the impeller vane or only a portion of the vane rotates around another axis or rotation, maintaining a continuous vane. This closes or opens the outlet ports, which increases or decreases the pressure at the WF injection radius (dashed circular line). An additional optional geometry change may be the depth of the converging-diverging section (gray narrowing at a radius larger than the dashed line), which can be realized mechanically with a spring that closes the gap at lower pressure levels. Another option may be a fluid injection into the narrowing section when the pressure drops below the nominal value.

[0128] A detailed description of the turbine:

[0129] 1. Rotor leg is submerged In HTL reservoir, the HTL is sucked into the rotor.

[0130] 2. The first section of the rotor is similar to a centrifugal pump impeller. The HTL is pressurized due to the force exerted by the rotor vanes until reaching a maximal static pressure at the beginning of the WF injection section (dashed circle).

[0131] 3. Pressurized WF is injected, optionally from the top through a hollow shaft, and mixed at the injection section with the HTL.

[0132] 4. If using liquified WF: after mixing with the HTL, the WF starts to evaporate, optionally at a constant pressure close to the saturation pressure of the WF at the HTL temperature.

[0133] 5. In the nozzle section, the mixture of a gaseous WF and HTL accelerates due to the geometry of the vanes, the pressure drops, the WF expands and further accelerates the mixture. During the mixture expansion, supersonic velocity is achieved.

[0134] 6. At the outlet of the rotor, the j ets flow almost tangentially and create a thrust force that creates a moment on the shaft.

[0135] The rotor is a closed disc with vanes along it, the following is a description of the different sections in the rotor.

[0136] HTL - suction and pressure increase (impeller): the purpose of this section of the rotor is to pressurize the required HTL flow rate before it gets mixed with the WF. The way to do so is similar to a centrifugal pump impeller, the rotating vanes accelerate the liquid, and by slowing it after the impeller the pressure increases. • rt- the radius at the rotor inlet

[0137] • r2- the radius at the end of the impeller, before WF injection

[0138] • P - vane angle from the tangential direction

[0139] • u - impeller velocity, u = a> • r

[0140] • a> - rotation speed [rad / s]

[0141] • V - absolute velocity of the fluid

[0142] • W - relative velocity of the fluid (at a rotating coordinate system)

[0143] • The notations ‘r' and 't' are for radial and tangential directions respectively.

[0144] • b - flow passage height

[0145] • wt - vane wall thickness at the tangential direction

[0146] • z - number of vanes

[0147] Flow rate is due to radial velocity only, from mass conservation:

[0148] (1) VHTL= Vr■ A = Vr■ b(2nr — z • wt)

[0149] In a rotating system:

[0150] (2) Wr= Vr

[0151] (3) Vt= U - Wt

[0152] The relative velocity W is parallel to the vane:

[0153] In most cases r1Vti« 0

[0154] In terms of power:

[0155] This is the power that the vanes give to the fluid, from energy conservation we can find the fluid head: We can see from the equations above that by choosing the geometry (b, r, , wt) and rotation speed (m) and by accounting for losses we get the required pressure at the injection and the HTL flow rate.

[0156] HTL + WF vapors expansion: the purpose of this part of the rotor is to drop the pressure of the two-phase mixture while the WF expands isothermally. The work done by the WF accelerates the mixture and creates thrust force at the rotor outlet.

[0157] The following presents the conservation equations for the two-phase flow part of the rotor, solving these equations at each point (radius) allows to determine the geometry for a required pressure profile P(r). On the contrary, we can calculate the pressure profile for a given geometry.

[0158] Assumptions:

[0159] • Changes in the flow properties occur at the radial direction only (no tangential gradients).

[0160] • Isothermal expansion.

[0161] • We assume friction losses of the mixture with the rotor walls.

[0162] The total flow rate of the Phases: (8) VLoLa[= VHTL+ VWFvapors

[0163] When VWFvaporsis a function of the changing pressure: (9) VWFvapors=

[0164] From continuity: (10) Vtotai= Vr• A = Vr• b(2n:r — z • wt)

[0165] The energy conservation equation:

[0166] The mixture energy at a specific point: (12) Ecurr= Pcurr■ VHTL+ (mHTL+

[0167] When Pcurris the static pressure at current point calculated.

[0168] The mixture energy at the inlet of the rotor: (13) Einiet= PtUrbine housing ’ VHTL

[0169] The potential energy from isothermal expansion of the WF:

[0170] When scurrand sinj are the WF entropies at the current point and at the injection respectively, and hcurr, hinj are the WF enthalpies at the current point and at the injection respectively.

[0171] The energy transferred from / to the rotor vanes at the current point calculated: From equation (11 )-( 15) we get the energy conservation equation:

[0172] + (™HTL + mWF) - U - Vt

[0173] From solving these equations, we get that both subsonic and supersonic flow can be achieved.

[0174] For the supersonic case, in conventional DLN reaching supersonic conditions is achieved by a converging-diverging geometry, in the omnidirectional DLN the change in radius leads to a change in momentum, and that accelerates the mixture without the need for converging-diverging geometry. This fact enables us to drop the pressure and reach supersonic conditions by a combination of two different geometry properties, one is convergence-divergence of the nozzle’s height (b(r)), and the other is by changing the vane angle ( / ?(?')) which change the relations between static and dynamic pressure. The change in radius leads to a change in momentum and by that accelerates the mixture without converging geometry. This enables to drop the pressure and reach supersonic conditions in combination with two different geometry properties, one is convergencedivergence of the rotor height (b(r)), and the other is by changing the vane angle ( / ?(?')) which change the relations between static and dynamic pressure.

[0175] Other requirements:

[0176] • A straight section at the end (constant b) to avoid axial flow at the outlet.

[0177] • Near tangential flow at the rotor outlet (small angle ft)

[0178] • In order to ensure minimal tangential gradients of the flow, we require that / ?of the leading and trailing edges will be equal. This property can be ensured by maintaining a nearly constant vane wall thickness (wt).

[0179] • Wall thickness should be thick enough to withstand the stresses.

[0180] • Avoid shockwave. Poutlet Pturbine housing

[0181] Gaseous WF injection: the injection section is designed to maintain a constant static pressure as a result of the WF boundary condition before the injection. This feature results in acceleration along the injection which can be achieved with many different combinations between the vane angle - , height - b and vane wall thickness - wt. For high heat transfer rate from the HTL to the WF bubbles, a small initial bubble size and a uniform distribution of the bubbles in the mixture is required. There are some parameters that can affect these requirements:

[0182] • Injection hole size and shape.

[0183] • HTL and WF velocity.

[0184] • Fluid properties.

[0185] • Reynolds number.

[0186] Liquified WF injection: when entering the chamber before injection, the WF gets pressurized as a result of the centrifugal force due to the increased radius. The work for this pumping effect is done by the rotor either via friction or a set of vanes specifically for the WF in this chamber. The pressure that is built in this chamber can be dropped on the injection holes (thereby allowing small injection holes) or be used to decrease the work done by the WF pump before entering the pre-injection chamber. Potentially, no pump would be needed because all the pressure increase can be done by the friction / vanes in the chamber. Note that the pressure inside the chamber needs to be sufficiently high to ensure that there is no evaporation of the WF before injection into the HTL. This may make it necessary to design the inlet into the chamber to be at saturation pressure, and all pressure increases between the center axis of rotation until the radius of injection needs to be dropped on the injection holes.

[0187] Optionally, the liquid WF is injected at high temperature and at sufficiently high pressure to maintain it in a liquid form. Optionally, a pump maintains the WF in a liquid form at the WF temperature. Optionally, the WF injection is from holes from the sides of the mixing chamber. Optionally, WF is injected into the HTL through channels that reduce some of the pressure. Optionally, the WF is injected into the HTL through pipes that reach the center of the mixing area. Optionally, the pipes have side holes that inject the liquid WF into the HTL evenly in the vertical direction. Optionally, a few such pipes inject the liquid WF evenly into the mixing chamber. The head losses due to the pipes are minor due to the low-velocity area. A mixing chamber geometry is optionally designed to maintain a fixed static pressure, optionally, by conversion section. Optionally, the injection area is part of the mixing chamber. The De-Laval converging-diverging section is at the outer diameter after the mixing chamber. Figure 5 depicts such pipes for liquids but, optionally, evaporation occurs before the mixing. Optionally, the liquid WF enters the turbine from its axis of rotation and passes through WF vanes that reduce or increase the pressure for the liquid WF to reach the HTL at the same pressure as the HTL.

[0188] When injecting liquified WF, equation (13) is modified to include the WF pressure energy at the injection:

[0189] Evaporation (for liquid WF only): when the liquid WF first comes into contact with the HTL, the first process is temperature equalization in which heat is extracted from the HTL. This is done between two liquid phases, so the heat transfer rate is expected to be high.

[0190] Next, evaporation occurs with further heat extraction from the HTL. In order to allow phase change to happen near the saturation point, the evaporation chamber is optionally kept at a constant pressure by changing the geometry to allow volume for both phases and giving all the extra energy from the increased radius to the velocity of the mixture with optionally minimal energy is converted to the pressure of the mixture. Note that there is also a term in the energy related to the VwF,iiq-Pmj which exists before the evaporation but does not after the evaporation. This term also adds to the velocity at the end of the evaporation as opposed to the beginning of the evaporation.

[0191] As mentioned above, the present disclosure provides another solution for dealing with the head losses. This solution includes curving the nozzle. The streamlines of the flow are not pure omnidirectional, partially due to the presence of veins which break the omnidirectional symmetry. Under this regime, the solution is a mixture of the omnidirectional and the conventional one. It is important to eliminate non-symmetrical forces on the bubbly flow, which may separate the flow or cause a non-uniform pressure. Therefore, the nozzle is optionally curved to support a mixture flow in a straight line in the inertial system, which minimizes head losses. The only nonideal mixture flow in a straight-line results from the different radial distances of different streamlines, which requires different curves for each streamline. The solution is calculating the straight line for the center of mass (See Fig. 6). Each curve for each streamline is calculated separately, and the envelope of the curves is the geometry of the nozzle. This may cause pressure and velocity changes that need to be optimized by reducing or expanding the nozzle crosssection while maintaining the center of mass streamline unchanged. Fig. 8 depicts the center of mass streamline in both the inertial and rotating systems. Tl, T2, . . . T5 describe propagating locations of a controlled volume flowing in the nozzle, as a straight streamline flow in the inertial system at different times. The notations tl, t2,..t5 are the locations of the mixing chamber at the same sampled times. When the controlled volume is at the locations Tl, T2,..T5, the mixing chamber is at tl, t2, ...t5 correspondingly. Three parts of the nozzle can be identified. First nozzle part, just after the mixing chamber, the controlled volume tangential velocity is slower than the nozzle tangential velocity, and the radial distance increases with the flow. The controlled volume accelerates until reaching the nozzle tangential velocity. At this moment, a second nozzle part starts, where the radial distance of the controlled volume and the nozzle is reduced. This part continues until the controlled volume returns to about the initial mixing chamber location and therefore the initial radial distance from the axis of rotation. That is, the location T4 is the same or close to Tl. A third nozzle part starts at this moment, where the radial distance increases with propagation. 4-nozzle curved dashed lines describe the streamline in the rotating system. The nozzle geometry follows this center of mass curved line. Optionally, only a portion of the nozzle curved line is realized. For example, radial first and second nozzle parts support radial streamline flow until the tangential velocity of the controlled volume exceeds the nozzle tangential velocity, and then a curved third nozzle part geometry maintains a straight streamline flow of the controlled volume at the inertial system.

[0192] The above results in a nozzle geometry that extends its mass-center distance from the center of the rotation axis as long as the tangential velocity is lower than the turbine tangential velocity (optionally, from the mixing section till the neck), and reduces its distance from the center of the rotation axis when the tangential velocity is faster than the turbine's tangential velocity (optionally, after the nozzle's neck).

[0193] Optionally, the straight streamline in the inertial system is within 0 deg, 5deg, lOdeg, 20deg, or 40deg tilt with respect to the tangential direction (direction of a rotating body) to avoid re-impinging of the jet in the turbine. Namely, the flow path is slanted along the flow direction. To eliminate the exiting jet from impinging on the turbine, the nozzle is optionally tilted at the axis of rotation direction, forming a spiral flow. That is the jet exits at a different plane than the impeller's plane.

[0194] Pre-impeller inducer: the rotating turbine's leg (the HTL inlet at the center of the impeller in the drawing) is optionally connected to a fixed base, which requires sealed bearings to prevent gas from entering the impeller through the leg. Inducing a positive pressure inside the leg eliminates such leaks. This is optionally achieved by a pre-impeller inducer located upstream (before) of the leak location that is between the rotating and the fixed interfaces. The inducer builds a positive pressure at the leg, blocking gas from entering the leg. Optionally, the pre-impeller is mechanically connected to the impeller and rotates with it.

[0195] In ramp-up conditions, the turbine is at low rotation velocity, having a low gradient of pressure. Yet, the HTL temperature may allow evaporation of WF at high pressure. This may cause a backflow ofWF into the impeller, which will arrest the turbine operation. To reduce backflow, the WF injection location is optionally located downstream to the high static -pressure location. Optionally, the section between the impeller's edge and the injection location of WF has a siphon (See Fig. 7), such that the distance from the rotation axis at the siphon is larger than the radial distance of the impeller edge and the radial distance of the injection location from the rotation axis. This induces higher pressure before the injection, which eliminates backflow also at low rotation velocity. Another option is reducing the static pressure before the WF injection location by increasing the flow velocity (dynamic pressure) at the expanse of the static pressure.

[0196] The ramp-up is done by removing the external load from the turbine. Optionally, using an external HTL pump that brings the turbine to an initial HTL flow rate and rotation velocity where pressure is built up and the WF injection further accelerates the turbine to its designed rotation velocity where the load is connected. Optionally, an external ramp-up motor is used to rotate the turbine to build up initial pressure and HTL flow rate, and the WF injection further accelerates the turbine to its designed rotation velocity. Optionally, the ramp-up motor is the turbine power generator operating as a motor. For example, an asynchronous generator operates as a motor when the rotation velocity is lower than the designed rotation velocity. Optionally, the injected pressure of gas / vapors is controlled to be maintained below the stagnation pressure at the injection location according to the specific rotation velocity and increases as the rotation velocity increases, until reaching the designed working point. Optionally, the HTL temperature is controlled to maintain the WF's vapor pressure below stagnation pressure, and the HTL is heated as the turbine accelerates to its design point. To eliminate the exiting jet from impinging on the turbine, the nozzle is optionally tilted at the axis of rotation direction, forming a spiral flow. That is, the jet exits at a different plane than the impeller's plane. The temperature of the WF before mixed with the HTL set the time and location of evaporation. Lower temperature results in a longer heating time, and longer downstream distance until evaporation starts. This degree of freedom can support isochoric or isobaric heating of the WF. Isochoric heating allows to reduce the power invested in the WF pump. Also, partial isochoric heating reduces WF pump losses by allowing injection at a lower static pressure location, while the evaporation is at higher static pressure. Optionally, the WF temperature is controlled by pre-heating the WF in an external heater. Optionally, the WF temperature is elevated by flowing the WF at the turbine while thermally connected to the hot HTL, as exemplified in Fig. 5. By designing the WF flow path and the heat transfer rate from the HTL to the WF, the evaporation starting location in the nozzle is controlled. Optionally the WF is injected as vapor. Optionally, the WF is injected into the HTL as liquid at a temperature lower than the saturation temperature by about 5°C, 10°C, 20°C, 40°C, or 80°C. Optionally, the WF temperature at the injection location is similar to the HTL temperature or lower by less than about 5°C, 10°C, 20°C, 40°C, or 80°C. Optionally, the WF is injected cold at a low static pressure location and evaporates at a higher static pressure location. Optionally, WF is injected before the siphon and the evaporation occurs after the siphon.

[0197] At ramp-up and off-design conditions (different HTL temperature, different HTL flow rate, different load on the turbine, different ambient temperature, etc.), a controllable nozzle is optionally used, where the ratio between the neck diameter and the nozzle exit diameter changes according to the De-Laval solution at the ramp up and off-design conditions. This control over the nozzle conditions is optionally obtained by narrowing or expanding the neck diameter at the converging-diverging nozzle, or a dynamic change of the nozzle exit diameter.

[0198] For some applications, a specific orientation of the turbine is preferred. Optionally the rotation axis is vertical, and optionally it is horizontal. For example, using the turbine in converting the waste heat to power in Marin applications. To avoid gyroscope extra load on the turbine bearings, the turbine rotation axis is preferred to be the direction (or opposite direction) of sailing. This way the roll doesn’t affect the turbine, while the pitch and the yaw conventionally have minor effects.

[0199] The term "about" should be interpreted as a deviation of ±20% of the nominal value. For example, if the value is about 10, thus it should be understood to be in the range of 8-12.

Claims

CLAIMS:

1. A turbine system, comprising: a rotatable turbine rotating about a rotation axis of rotation within an inertial frame of reference, and having a heat transfer liquid (HTL) inlet for introducing a stream of HTL, an impeller section in fluid communication with and radially peripheral to the HTL inlet to receive said stream of HTL, a nozzle section radially peripheral to the impeller section and defining one or more nozzles, and a working fluid (WF) injector for injection of pressurized WF into a mixing section for mixing a working fluid (WF) and the HTL to form a WF / HTL mixture, the mixing section is either defined in (i) the impeller section, (ii) the nozzle section or (iii) in a section linking the impeller section and the nozzle section; wherein the impeller section, the mixing section and the nozzle section define a center of mass flow path of the HTL and of the WF / HTL mixture, the nozzle is designed for (i) receiving the WF / HTL mixture from the mixing section, (ii) allowing isothermal or quasi-isothermal expansion of the WF thereby accelerating the WF / HTL mixture and (iii) ejection of the accelerated WF / HTL mixture from an outlet of the nozzle to induce rotation of the turbine, and wherein at a given operational rotational velocity of the turbine, at least a part of the center of mass flow path of a streamlined flow of a controlled volume of the WF / HTL mixture is a straight line in the inertial frame of reference.

2. The turbine system of claim 1, wherein for at least one first part of the center of mass flow path, in which a tangential velocity of flow along the center of mass flow path is lower than a tangential velocity of the turbine, a radial distance of the center of mass flow path from the rotation axis increases along a downstream direction of the flow path, for at least one second part of the center of mass flow path, in which the tangential velocity of the flow along the center of mass flow path is higher than the tangential velocity of the turbine, a radial distance of the center of mass flow path from the rotation axis decreases along a downstream direction of the flow path, and whereinthe first part and the second part are designed to create a straight line flow in the inertial frame of reference.

3. The turbine system of claim 2, wherein said first part of the center of mass flow path is upstream said second part of the center of mass flow path.

4. The turbine system of claim 2 or 3, wherein for at least one third part of the center of mass flow path within the nozzle section, in which a tangential velocity of the flow along the center of mass flow path is higher than the tangential velocity of the turbine, a radial distance of the center of mass flow path from the rotation axis increases along a downstream direction of the flow path, and wherein said at least one third part of the center of mass flow path is downstream said at least one second part of the center of mass flow path.

5. The turbine system of any one of claims 1 -4, wherein the nozzle section comprises a radial distance increasing part, in which the center of mass flow path radial distance from the rotation axis increases, and a radial distance decreasing part downstream the radial distance increasing part and, in which the center of mass flow path radial distance from the rotation axis decreases.

6. The turbine system of claim 5, wherein the radial distance increasing part defines a first nozzle part in which distance of its center of mass from the rotation axis increases, and the radial distance decreasing part defines a second nozzle part, the second nozzle part in which distance of its center of mass from the rotation axis decreases.

7. The turbine system of any one of claims 1-6, wherein the HTL inlet is at the rotation axis.

8. The turbine system of any one of claims 1-7, wherein the nozzle is a de Laval nozzle having a de Laval nozzle geometry.

9. The turbine system of any one of claims 2-8, wherein the at least one first part of the center of mass flow path or the radial distance increasing part is defined between the mixing section and a neck of the nozzle, and the at least one second part of the center of mass flow path or the radial distance decreasing part is defined between the neck of the nozzle and the outlet of the nozzle.

10. The turbine system of any one of claims 1-9, wherein the increase or decrease profile of the radial distance of the center of mass flow path from the rotation axis in eachselected location is dependent on the difference between the tangential velocity of the flow along the flow path and the turbine tangential velocity.

11. The turbine system of any one of claims 1-10, wherein the outlet of the nozzle is tilted with respect to an impeller plane defined by the impeller section so as to eject the WF / HTL mixture below or above the impeller.

12. The turbine system of any one of claims 1-10, wherein the impeller defines an impeller plane and outlet of the nozzle is located on an outlet plane parallel to and different from the impeller plane.

13. The turbine system of claim 12, wherein the outlet plane is lower than the impeller plane.

14. The turbine system of claim 12 or 13, wherein the nozzle has a tilt profile with respect to the impeller plane such that it gradually decreases its height until reaching the outlet plane.

15. The turbine system of any one of claims 1-14, comprising a WF flow line fluidically coupled upstream to the WF injector for allowing a flow of WF to the WF injector, wherein the WF flow line is in thermal contact with portions of the impeller section for allowing heat exchange between the HTL flowing in the impeller section and WF flowing in the WF flow line.

16. The turbine of any one of claims 1-15, comprising a WF heater fluidically coupled upstream to the WF injector for controllably heating the WF.

17. The turbine of any one of claims 1-16, comprising a siphon section that comprises a siphon arrangement, the siphon section is located between the impeller section and the mixing section.

18. The turbine of any one of claims 1-17, wherein the mixing section is downstream of a highest static-pressure location defining the location in which the static pressure is the highest.

19. The turbine system of any one of claims 1-18, comprising a pre-impeller inducer upstream the HTL inlet for inducing positive pressure in a HTL flow line that is fluidically coupled to the HTL inlet.

20. The turbine system of any one of claims 1-19, comprising a HTL flow line fluidically coupled upstream to the HTL inlet at a first end thereof and is coupled to a fixed base at a second end thereof with sealed bearings, wherein the HTL flow line is rotatable with the turbine rotation.

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